It is not currently possible to move focus between an embedder and guest unless they each have more than a main frame. Focus change between web contents require a frame focus change in the target which is incorrect.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9993fca0084ba71c628918b384ac701fe6514e44

commit 9993fca0084ba71c628918b384ac701fe6514e44
Author: avallee <avallee@chromium.org>
Date: Thu Nov 17 06:16:50 2016

<webview>: Correctly shift focus between WebContents.

http://crrev.com/408445 Fixes some cases of keyboard input but required
a renderer initiated frame focus change in order to do so.

This change assumes that the browser is the primary driver of
WebContents level focus changes. The leftover FrameHost*::OnFrameFocused
is left so that an embedder can script aWebview.focus() to give focus.

BUG= 660044 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2451143003
Cr-Commit-Position: refs/heads/master@{#432781}

[modify] https://crrev.com/9993fca0084ba71c628918b384ac701fe6514e44/chrome/browser/apps/guest_view/web_view_interactive_browsertest.cc
[modify] https://crrev.com/9993fca0084ba71c628918b384ac701fe6514e44/chrome/test/data/extensions/platform_apps/web_view/focus/embedder.js
[modify] https://crrev.com/9993fca0084ba71c628918b384ac701fe6514e44/chrome/test/data/extensions/platform_apps/web_view/focus/inject_focus.js
[modify] https://crrev.com/9993fca0084ba71c628918b384ac701fe6514e44/content/browser/frame_host/frame_tree.cc
[modify] https://crrev.com/9993fca0084ba71c628918b384ac701fe6514e44/content/browser/renderer_host/render_widget_host_delegate.cc
[modify] https://crrev.com/9993fca0084ba71c628918b384ac701fe6514e44/content/browser/renderer_host/render_widget_host_delegate.h
[modify] https://crrev.com/9993fca0084ba71c628918b384ac701fe6514e44/content/browser/renderer_host/render_widget_host_impl.cc
[modify] https://crrev.com/9993fca0084ba71c628918b384ac701fe6514e44/content/browser/renderer_host/render_widget_host_impl.h
[modify] https://crrev.com/9993fca0084ba71c628918b384ac701fe6514e44/content/browser/web_contents/web_contents_impl.cc
[modify] https://crrev.com/9993fca0084ba71c628918b384ac701fe6514e44/content/browser/web_contents/web_contents_impl.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4efd8dc094dc1b000c8aa01ffe691e57732a8397

commit 4efd8dc094dc1b000c8aa01ffe691e57732a8397
Author: avallee <avallee@chromium.org>
Date: Thu Nov 17 17:48:59 2016

Remove FrameMsg_ClearFocusedFrame.

https://codereview.chromium.org/2451143003/ removes the dependency on
this message.

 - Remove FrameMsg_ClearFocusedFrame
 - Remove WebView::unfocusDocumentView
 - Remvoe RenderFrame::ClearFocusedFrame

BUG= 660044 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2455133005
Cr-Commit-Position: refs/heads/master@{#432906}

[modify] https://crrev.com/4efd8dc094dc1b000c8aa01ffe691e57732a8397/content/browser/frame_host/render_frame_host_impl.cc
[modify] https://crrev.com/4efd8dc094dc1b000c8aa01ffe691e57732a8397/content/browser/frame_host/render_frame_host_impl.h
[modify] https://crrev.com/4efd8dc094dc1b000c8aa01ffe691e57732a8397/content/common/frame_messages.h
[modify] https://crrev.com/4efd8dc094dc1b000c8aa01ffe691e57732a8397/content/renderer/render_frame_impl.cc
[modify] https://crrev.com/4efd8dc094dc1b000c8aa01ffe691e57732a8397/content/renderer/render_frame_impl.h
[modify] https://crrev.com/4efd8dc094dc1b000c8aa01ffe691e57732a8397/third_party/WebKit/Source/web/WebViewImpl.cpp
[modify] https://crrev.com/4efd8dc094dc1b000c8aa01ffe691e57732a8397/third_party/WebKit/Source/web/WebViewImpl.h
[modify] https://crrev.com/4efd8dc094dc1b000c8aa01ffe691e57732a8397/third_party/WebKit/public/web/WebView.h